ELECTROLYSIS OF CHLORIDE WITH FLUORINE POLYMER MEMBRANE WITH CARBOXYLIC ACID GROUPS

摘要

An electrolysis of an aqueous solution of an alkali metal chloride is carried out to produce an alkali metal hydroxide, in relatively low concentration lower than 30 wt. % and chlorine by using a modified cation exchange membrane made of a fluorinated polymer having carboxylic acid type ion exchange groups, which has an ion exchange capacity of 1.1 to 2.0 meg/g. dry polymer, at least one surface layer of the modified membrane having a lower ion exchange capacity than the unmodified part of the membrane which lower ion exchange capacity is desirably from 45 to 95% of that of the unmodified part of the membrane. Thus the present invention provides an electrolysis of an aqueous solution of an alkali metal chloride to produce an alkali metal hydroxide in relatively low concentration and chlorine at high current efficiency and low voltage.